Honestly, after Halo's collapse I'm shocked that he did end up trying with Alien (and then again with Robocop) at all.
I do feel bad for him in this situation, 'cause I'm genuinely into his style and really like District 9 and Chappie and some of the Oats stuff, but as much as I think he could have done a very good Alien movie, I don't think the particular one he was working on (based on what we had seen in the released concept art) would have been for me at all.
His Robocop movie's cancelation honestly still feels to me like a much, much bigger loss than his Alien movie's cancelation, to be quite honest. A Blomkamp-directed Robocop, satirizing the current socio-political climate, is something I was all over from day one.
I'm going to check out his new movie, Demonic, today I think.